Conventional luminous floats have been used as floating lights and beacon lights on the ocean. For those of small or medium size, a battery is used as a source of electricity, and those of large sizes are provided with wind-power electricity generating devices, etc.
Furthermore, luminous floats with built-in wave-power electricity generating devices which generate electricity for the emission of light by means of utilizing a vertical motion of the waves, etc., have been invented.
Luminous floats of such construction as stated above have the following serious problems.
That is, in the case of a luminous float using a battery as a source of electricity, the capacity of supplying electric power is markedly low, and since the battery becomes dead in a short period of time, the replacement of the dead battery must be frequently performed. As a matter of fact, it requires much labor involving a lot of difficulties as well as a substantial amount of financial burden.
What is further important to note is that the replaced battery is thrown away into the ocean so that the leakage of an electrolyte from the inside of the battery causes environmental contamination, which is a problem that cannot be overlooked; but, in reality, no countermeasure has been taken.
On the other hand, in the case of a luminous float capable of wind-power electricity generation, the apparatus itself is constructed on an extremely large scale and an enormous cost is required for equipment investment. Seawater containing salt and the sea breeze accelerate erosion, etc, on parts of the apparatus. Said parts must be heaved one by one for inspection for maintenance, and the number of times this heaving work is performed has been inevitably increased.
Moreover, in the case of a luminous float capable of wave-power electricity generation, what has been pointed out as a problem is that electricity cannot be generated at all when the sea is calm.
Any of the above problems is peculiar to the field of technology to which the luminous float pertains, in that the luminous float is provided on the ocean where electric power cannot be easily supplied, unlike the supply of electric power on land.